1. Field of the Invention
This invention relates to portable entertainment devices. In particular, it relates to power management techniques in portable entertainment devices such as MP3 players, video players, portable jukeboxes, etc.
2. Background of Related Art
The world has been transformed by the emergence of portable entertainment devices, especially by the explosion of players of compressed music files, in particular those files compressed using the ever-popular MPEG3 (“MP3”) encoding for music, compressed video files, etc.
FIG. 8 shows a conventional MP3 player.
In particular, as shown in FIG. 8, an MP3 player 400 includes a processor 102, a clock 104 such as a crystal or oscillator, used to set the processor MIPS speed, a CODEC 106 and output speaker 108. Entertainment data 112 is stored in the MP3 device 400, e.g., in non-volatile memory, on a removable media card or removable memory card, floppy disk, internal or external hard drive, etc. Batteries 120 installed in the MP3 player 400 allow portable use of the MP3 player 400. A user operates various buttons (not shown) on the MP3 player 400 to instruct it to queue up certain songs or other entertainment data files, placing either a list of songs to be played, or copies of the song files themselves, in a song queue 110.
Conventional portable entertainment devices utilize a processor clock 104 having a fixed speed. Generally, designers of conventional portable entertainment devices choose the fixed clock speed based on maximum needs or peak demands.
Thus, conventional designers of portable entertainment devices choose a processor clock having a speed which addresses the needs (usually measured in Million Instructions Per Second (MIPS)) of a software algorithm.
However, the present inventor appreciates that this will result in the clock running faster than required during playback of many files. Over long periods of time, this excessive speed results in wasted power.
There is a need for solutions to the short battery life in portable media players such as MP3 players.